Jones Sextant

This form of sextant was introduced in the 1790s and was still popular in the middle decades of the nineteenth century. The inscription on this example reads "W. & S. Jones. 30 Holborn London." W. & S. Jones described it as being "so framed, as not be liable to warped or strained, with adjusting screws, telescopes, and other auxiliary apparatus, the most proper for taking distances accurately, to determine the longitude at sea, &c."
This example belonged to Colby College in Waterville, Maine, and may have been acquired soon after that school was chartered in 1813. The silvered scale is graduated every 10 minutes from 0° to +130° and read by vernier with tangent screw and swinging magnifier.
Ref: George Adams, Geometrical and Graphical Essays, 2nd edition revised by William Jones (London, 1797), pp. 271-284.
Encyclopaedia Britannica (Edinburgh, 1797), vol. 12, art. "Navigation," p. 737.
W. & S. Jones, A Catalogue of Optical, Mathematical, and Philosophical Instruments, appended to G. Adams, An Essay on Electricity (London, 1799).
Currently not on view
Object Name
date made
early 19th century
W. & S. Jones
radius: 8 1/2 in; 21.59 cm
place made
United Kingdom: England, London
ID Number
catalog number
accession number
Measuring & Mapping
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Colby College
Additional Media

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